I would not go green. You'd have to get the EXACT tone to match it, otherwise it will look awful. And if your shopping online the pics can be deceiving of what tone it actually is. I think a black pant would look clean and is probably the best choice.
edit: a darker brown might not look bad.
I am a total picky ass. I have been known spend weeks shopping at dozens of different stores just to get stuff that matches perfectly. lol Yeah...I am a girl. My jacket is pink and orange, and I ended up knitting my own beanie just to make sure that the colors matched exactly. Even bought a sports watch that matched perfectly. I am a little crazy that way. So for me to say "green" I guess I didnt take into account that not everyone is going to be as insane as I am.